1. Field of the Invention
This invention relates to ball capture joints. More specifically, the invention is a passive ball capture joint that can be positively and rigidly locked into position once capture has occurred and that includes an ejection mechanism when the joint is to be uncoupled.
2. Description of the Related Art
A wide variety of xe2x80x9csnap togetherxe2x80x9d joint couplings are known in the art. Included in this class of joints are ball-type joints which are often used in automotive linkages. Such ball joints are characterized by low cost and very low strength in the axial direction as they are generally used to transmit forces in a plane normal to the installation axis. Further, these joints are not generally considered useful as passive capture joints since they require more force to assemble than they can safely transmit in the axial direction.
A snap-fit ball joint design that can be used as a passive capture joint having three degrees of freedom is disclosed in U.S. Pat. No. 6,186,693. In this particular passive capture joint, a joint ball mounted on a stem is received in an inventive socket. The socket consists of a base having an exterior wall and forms an interior chamber having a top end, a bottom end and an interior wall. The interior chamber is open at the top end and forms a spherical cup at the bottom end. The socket base""s interior chamber is sized to accept the joint ball. The base also forms at least one bore at an acute angle away from the interior chamber""s open end. The bores have a first opening in the interior wall of the chamber and a second opening in the exterior wall of the base. Retaining balls sized to fit within the bores, but to only partially pass through the first opening, are movably housed within the bores. The retaining balls are movably held in the first opening by a compression spring housed in the bore. As the joint ball is inserted in the chamber, it forces the retaining balls back into the bore until the equator of the joint ball passes. Because the bore is at an acute angle to the interior chamber, the joint ball cannot exit the chamber without the joint being unlocked. The joint is manually unlocked by rotating a locking ring which encircles the base and covers the second opening. The locking ring has a radial slot for each retaining ball. The radial slot is disposed angularly from the base and is sized to allow passage of the retaining ball in the radial direction when the locking ring is manually rotated to align the radial slot with the second opening. However, there are many applications (e.g., space vehicle docking, underwater capture, etc.) that do not lend themselves to the above-described manual unlocking structure. Further, certain capture applications require a rigid joint once capture has occurred.
Accordingly, it is an object of the present invention to provide a passive ball capture joint.
Another object of the present invention is to provide a passive ball capture joint having a mechanized unlocking structure.
Still another object of the present invention is to provide a passive ball capture joint having a mechanized structure for making the joint a rigid one.
A still further object of the present invention is to provide a passive ball capture joint that facilitates ejection of the captured ball once the joint has been unlocked.
Other objects and advantages of the present invention will become more obvious hereinafter in the specification and drawings.
In accordance with the present invention, a passive ball capture joint has a sleeve defining a first open end and a second open end opposing one another along the sleeve""s longitudinal axis. The sleeve has a plurality of bores distributed about a circumference thereof and formed therethrough at an acute angle relative to the longitudinal axis. The acute angle is such that it diverges outward from the sleeve""s longitudinal axis in a direction defined by the sleeve""s first open end to its second open end. A spring-loaded retainer is slidingly fitted in each bore and is biased such that, if allowed, will extend at least partially into the sleeve. A receiver, slidingly engaged in the sleeve second open end, has a cupped portion facing the sleeve""s first open end. A ring is rotatably mounted about the sleeve and intersects the bores. The ring has an interior wall defining a plurality of shaped races. Each race bears against one of the spring-loaded retainers. At a first rotational position of the ring, each race permits its respective spring-loaded retainer to achieve a first position defined by at least partial extension into the sleeve. At a second rotational position of the ring, each race permits its respective spring-loaded retainer to achieve a second position defined by the spring-loaded retainer being positioned further radially outward from the sleeve""s longitudinal axis as compared to the first position. A mechanized axial force producer is coupled to the receiver to apply an axial force thereto so that the receiver is biased towards the sleeve""s first open end. A mechanized rotational force producer is coupled to the ring to apply a rotational force thereto so that the ring can be rotated from its first rotational position to its second rotational position.
In order to capture a joint ball, the ring is in its first rotational position. Once captured, the receiver is pressed axially against the joint ball to firmly seat the joint ball between the receiver and the spring-loaded retainers. When the joint ball is to be ejected, the ring is rotated to its second rotational position while the receiver continues to have the axial force applied thereto. As a result, each spring-loaded retainer is moved from its first position to its second position as the joint ball moves axially out of the sleeve.